The invention relates to a process for the production of high purity carbon monoxide, especially a process capable of producing both high-purity hydrogen and high-purity carbon monoxide.
A known process of this type, for example, comprises the separation of an extensively dry, for example, not more than 0.1 mol-ppm H.sub.2 O, and substantially CO.sub.2 -free, for example, not more than 0.1 mol-ppm CO.sub.2, H.sub.2 /CO crude gas mixture, also containing methane in an amount of from 1 mol % to 7 mol %, by means of pressure swing adsorption and one-stage partial condensation, wherein the H.sub.2 /CO crude gas mixture is subjected to a pressure swing adsorption process, producing a high-purity hydrogen product stream, while the CO-rich gas obtained by desorption during regeneration in the pressure swing adsorption process is compressed, cooled, at least partially condensed, and conducted into a phase separator wherein it is separated into a gaseous H.sub.2 -rich fraction and a liquid CO-rich fraction, whereupon the gaseous H.sub.2 -rich fraction is heated and admixed to the H.sub.2 /CO crude gas mixture before the latter is fed into the pressure swing adsorption system.
A number of technical modifications have occurred in recent years in the H.sub.2 /CO fractionation art, owing to increased demands for purity of the fractionation products, the increased importance of the operating costs of a facility, and the continuous improvement in the thermodynamic data available.
The H.sub.2 /CO crude gas mixture is primarily obtained from steam reforming processes. However, heavy oil gasification with oxygen--i.e., a partial oxidation--has likewise gained significance as a source of H.sub.2 /CO crude gas, presupposing an inexpensive oxygen source.
A major portion of the carbon monoxide produced by the process can be utilized in formic and acetic acid production. Another field of use is in polycarbonate chemistry which requires, as a raw material, phosgene of high purity, which requires, in turn, carbon monoxide of maximum purity. The methane content of the carbon monoxide portion here must be lower than 10 mol ppm, the hydrogen content lower than 1000 mol ppm. The hydrogen produced by the process can be used for a great variety of hydrogenation purposes.
An overview regarding the processes being used for manufacturing pure carbon monoxide and pure hydrogen is presented in the article by Dr. Ralph Berninger in "LINDE Reports on Science and Technology" No. 44, 1988, pages 18-23.
One disadvantage of prior processes is that at least two distillation columns are necessary to remove both H.sub.2 and CH.sub.4 from CO, resulting in a corresponding number of conduits, valves and the concomitant control and regulating devices. This, of course, increases the susceptibility of the process to breakdown or malfunction.